1. Field of the Invention
In one of its aspects, the present invention relates to a cleaning apparatus for use in a fluid treatment module. In another of its aspects, the present invention relates to a radiation source module comprising the cleaning apparatus.
2. Description of the Prior Art
Fluid treatment systems are known generally in the art.
For example, U.S. Pat. Nos. 4,482,809, 4,872,980 and 5,006,244 (all in the name of Maarschalkerweerd and all assigned to the assignee of the present invention and hereinafter referred to as the Maarschalkerweerd #1 Patents), the contents of each of which are hereby incorporated by reference, all describe gravity fed fluid treatment systems which employ ultraviolet (UV) radiation.
Such systems include an array of UV lamp frames which include several UV lamps each of which are mounted within sleeves which extend between and are supported by a pair of legs which are attached to a cross-piece. The so-supported sleeves (containing the UV lamps) are immersed into a fluid to be treated which is then irradiated as required. The amount of radiation to which the fluid is exposed is determined by the proximity of the fluid to the lamps, the output wattage of the lamps and the fluid""s flow rate past the lamps. Typically, one or more UV sensors may be employed to monitor the UV output of the lamps and the fluid level is typically controlled, to some extent, downstream of the treatment device by means of level gates or the like.
However, disadvantages exist with the above-described systems. Depending upon the quality of the fluid which is being treated, the sleeves surrounding the UV lamps periodically become fouled with foreign materials, inhibiting their ability to transmit UV radiation to the fluid. For a given installation, the occurrence of such fouling may be determined from historical operating data or by measurements from the UV sensors. Once fouling has reached a certain point, the sleeves must be cleaned to remove the fouling materials and optimize system performance.
If the UV lamp modules are employed in an open, channel-like system (e.g., such as the one described and illustrated in Maarschalkerweerd #1 Patents), one or more of the modules may be removed while the system continues to operate, and the removed frames may be immersed in a bath of suitable cleaning solution (e.g., a mild acid) which may be air-agitated to remove fouling materials. Of course, this necessitates the provision of surplus or redundant sources of UV radiation (usually by including extra UV lamp modules) to ensure adequate irradiation of the fluid being treated while one or more of the frames has been removed for cleaning. This required surplus UV capacity adds to the capital expense of installing the treatment system. Further, a cleaning vessel for receiving the UV lamp modules must also be provided and maintained. Depending on the number of modules which must be serviced for cleaning at one time and the frequency at which they require cleaning, this can also significantly add to the expense of operating and maintaining the treatment system. Furthermore, this cleaning regimen necessitates relatively high labor costs to attend to the required remnoval/re-installation of modules and removal/re-filling of cleaning solution in the cleaning vessel. Still further, such handling of the modules results in an increased risk of damage to or breakage of the lamps in the module.
If the frames are in a closed system (e.g., such as the treatment chamber described in U.S. Pat. No. 5,504,335 (in the name of Maarschalkerweerd and assigned to the assignee of the present invention), the contents of which are hereby incorporated by reference), removal of the frames from the fluid for cleaning is usually impractical. In this case, the sleeves must be cleaned by suspending treatment of the fluid, shutting inlet and outlet valves to the treatment enclosure and filling the entire treatment enclosure with the cleaning solution and air-agitating the fluid to remove the fouling materials. Cleaning such closed systems suffers from the disadvantages that the treatment system must be stopped while cleaning proceeds and that a large quantity of cleaning solution must be employed to fill the treatment enclosure. An additional problem exists in that handling large quantities of cleaning fluid is hazardous and disposing of large quantities of used cleaning fluid is difficult and/or expensive. Of course open flow systems suffer from these two problems, albeit to a lesser degree.
Indeed, it is the belief of the present inventors that, once installed, one of the largest maintenance costs associated with prior art fluid treatment systems is often the cost of cleaning the sleeves about the radiation sources.
U.S. Pat. No. 5,418,370, 5,539,210 and 5,590,390 (all in the name of Maarschalkerweerd and all assigned to the assignee of the present invention and hereinafter referred to as the Maarschalkerweerd #2 Patents), the contents of each of which are hereby incorporated by reference, all describe an improved cleaning system, particularly advantageous for use in gravity fed fluid treatment systems which employ UV radiation. Generally, the cleaning system comprises a cleaning sleeve engaging a portion of the exterior of a radiation source assembly including a radiation source (e.g., a UV lamp). The cleaning sleeve is movable between: (i) a retracted position wherein a first portion of radiation source assembly is exposed to a flow of fluid to be treated, and (ii) an extended position wherein the first portion of the radiation source assembly is completely or partially covered by the cleaning sleeve. The cleaning sleeve includes a chamber in contact with the first portion of the radiation source assembly. The chamber is supplied with a cleaning solution suitable for removing undesired materials from the first portion of the radiation source assembly.
The cleaning system described in the Maarschalkerweerd #2 Patents represents a significant advance in the art, especially when implemented in the radiation source module and fluid treatment system illustrated in these patents. However, implementation of the illustrated cleaning system in a fluid treatment module such as the one illustrated in the Maarschalkerweerd #1 Patents is problematic.
The reason for this is that the specific system illustrated in the Maarschalkerweerd #2 Patents is based a conventional rod/cylinder design (see especially FIG. 6 and the accompanying text in the Maarschalkerweerd #2 Patents). Specifically, the cleaning rings (308) are connected to a rod (328) disposed in a cylinder (312,314). In use the rod (328) is extended from or retracted into the cylinder (312,314) thereby moving the cleaning rings (308) over the quartz sleeve surrounding the ultraviolet lamp. Thus, when the rod (328) is extended to its extreme stroke end from the cylinder (312,314), the overall length of the rod and the cylinder is approximately twice as long as the rod stroke. While this approach dovetails nicely with the radiation source module and fluid treatment system illustrated in the Maarschalkerweerd #2 Patents, it is difficult to implement the fluid treatment module illustrated in the Maarschalkerweerd #1 Patents since, in the latter Patents, the lamp is supported at both ends by an opposed pair of legs. In such a case, the distance between the opposed pair of legs would have to be doubled to allow for provision of a conventional rod/cylinder design where a single wiper is used. This becomes impractical since a preferred embodiment of the module illustrated in the Maarschalkerweerd #1 Patents involves using a low pressure, ultraviolet radiation lamp which can be up to be about five feet in length to provide the necessary wattage of radiation. This mitigates against doubling the distance between the pair of opposed legs used to support the lamps.
In U.S. patent application Ser. No. 09/185,813 [Pearcey et al. (Pearcey)], filed Nov. 3, 1998 and the contents of which are hereby incorporated by reference, there is disclosed a cleaning apparatus for a radiation source module and a radiation source module incorporated such cleaning apparatus. Generally, the cleaning apparatus and related module comprise: (i) a slidable member magnetically coupled to a cleaning sleeve, the slidable member being disposed on and slidable with respect to a rodless cylinder, and (ii) motive means to translate the slidable member along the rodless cylinder whereby the cleaning sleeve is translated over the exterior of the radiation source assembly. The teachings of Pearcey represent a significant advance in the art, particularly when implemented in a fluid treatment module such as the one illustrated in Maarschalkerweerd #1 Patents.
Notwithstanding this, there remains a need in the art for a cleaning apparatus which obviates or mitigates at least one of the above-mentioned disadvantages of the prior art. It would be desirable to have such a cleaning apparatus which is particularly well suited for implementation on a fluid treatment module such as the one illustrated in the Maarschalkerweerd #1 Patents. More specifically, it would be beneficial to have a cleaning apparatus which facilitates radiation lamp replacement and which does not place undue forces on the radiation source assemblies cleaned thereby.
It is an object of the invention to provide a cleaning system which obviates or mitigates at least one of the above-mentioned disadvantages of the prior art.
Accordingly, in one of its aspects, the present invention provides a cleaning apparatus for a radiation source assembly in a fluid treatment system, the cleaning system comprising:
a carriage movable with respect to an exterior of the radiation source assembly;
at least one cleaning sleeve in sliding engagement with the exterior of the radiation source assembly, the at least one cleaning sleeve being moveable with respect to the carriage; and
drive means coupled to the carriage to translate the carriage whereby the at least one cleaning sleeve is translated over the exterior of the radiation source assembly.
In another of its aspects, the present invention provides radiation source module for use in a fluid treatment system, the module comprising:
a frame having a first support member;
at least one radiation source assembly extending from and in sealing engagement with the first support member, the at least one radiation source assembly comprising a radiation source:
cleaning means to remove undesired materials from an exterior of the at least one radiation source assembly, the cleaning means comprising:
a carriage movable with respect to an exterior of the radiation source assembly;
at least one cleaning sleeve in sliding engagement with the exterior of the radiation source assembly, the at least one cleaning sleeve being moveable with respect to the carriage; and
drive means coupled to the carriage to translate the carriage whereby the at least one cleaning sleeve is translated over the exterior of the radiation source assembly.
Thus, the present inventors have developed an improved cleaning apparatus useful in a radiation source module. Generally, the present cleaning apparatus comprises a cleaning sleeve which is movable with respect to the carriage that is driven to actuate the cleaning step. In a sense, the cleaning sleeve may be regarded as a xe2x80x9cfloatingxe2x80x9d cleaning sleeve movable with respect to the carriage (this will be discussed in more detail hereinbelow). An advantage of such an arrangement is particularly noted when the cleaning apparatus is used in a radiation source module having more than one radiation source assembly (e.g., each assembly may be regarded as a combination of a radiation lamp and a protective quartz sleeve). In this arrangement of the present cleaning apparatus, since the cleaning sleeves for each radiation source assembly are moveable independent of the carriage and of one another, there is a reduction in the lateral forces to which the radiation source assemblies are subjected. This minimizes breakage of the radiation source assemblies and reduces the lateral forces created on the radiation source assemblies and the minimum applied force required to actuate the cleaning apparatus. The result of this is to reduce the overall cost of constructing the cleaning apparatus in combination with a reduction in the cost to operate the apparatus (i.e., reduced energy costs). Further, this allows for a more compact design which helps reduce hydraulic head loss in the fluid treatment system in which the radiation source module is placed.
A further advantage of the individualized cleaning sleeve approach of a preferred embodiment of the present cleaning apparatus is that it allows for easier removable and replacement of the TV lamp without the requirement to xe2x80x9cbreakxe2x80x9d the seal between the cleaning sleeve and the radiation source. In other words, multiple or individual lamp removal can be achieved without breaching, in a preferred embodiment, the cleaning solution chamber in the cleaning sleeve. This results in reduction of cleaning solution waste and improved efficiency in lamp maintenance of the radiation source module.
A particularly preferred embodiment of the present cleaning apparatus involves providing a spacing between the cleaning sleeve and the carriage which allows the cleaning sleeve to xe2x80x9cfloatxe2x80x9d within the confines of the carriage in substantially the same direction that the carriage moves with respect to the radiation source assembly. More preferably, there is a gradient of such spacing between respective radiation source assemblies in a given module. Thus, the initial frictional force required to move the carriage is reduced. This is achieved by step-wise deferral of the frictional force which must be overcome to move each cleaning sleeve. Thus, the maximum necessary actuation force is reduced since only the static force of a fraction of the cleaning sleeves in the module must be overcome at a given time. The advantage here is an overall reduction in lateral forces to which the radiation source assembly is subjected and in the overall force needed to move the carriage. Further, this preferred embodiment allows for placement of the drive means above the series of radiation source assemblies in a given module.